A group of Hillary-philes has told the media not to use certain words when describing Clinton, including 'disingenuous.' But that's a handy word for a Beltway set that shies away from calling people 'liars.'

Disingenuous. The longtime political code word for “liar,” applying to someone who not only twists the truth but is seen as completely clueless in doing so.

“Disingenuous” is almost constantly in the news, but received new prominence this week in connection with Hillary Rodham Clinton. A pro-Clinton group called HRC Super Volunteers sent New York Times campaign reporter Amy Chozick a list of words it considered unacceptable in describing the likely Democratic presidential front-runner. “You are on notice that we will be watching, reading, listening and protesting coded sexism,” the e-mail warned.

The examples singled out included “secretive, polarizing, calculating, insincere, ambitious” – and “disingenuous.” While the group may consider that last word as a pejorative, the reality is that it’s often a polite way of insulting someone without having to be so unseemly. (A similarly deployed euphemism is “misleading.”)

“Disingenuous” also popped up when Jon Stewart last week slammedMitch McConnell, the Senate majority leader. The Kentucky lawmaker had criticized Democrats for delaying a sex-trafficking bill because of what Senator McConnell called the appeasement of “left-wing special interest groups.” Referring to antiabortion language that Republicans insisted be put in the bill, Mr. Stewart admonished McConnell for making “a disingenuous point”: “The only reason the language is in there is because you’re bowing down to right-wing special interests.”

Though this is quickly no longer becoming the case, it’s considered bad form – at least in person, as opposed to in print or online – to accuse someone of out-and-out prevarication. Then-Nebraska Democratic Sen. Bob Kerrey discovered this in 1996 when he described President Bill Clinton as an “unusually good liar” in a magazine interview. And, of course, South Carolina GOP Rep. Joe Wilson caused an even bigger furor when he shouted “You lie!” at President Obama during a 2009 speech.

Hence the popularity of “disingenuous.” When Steve Rothman found himself in 2012 having to run against fellow New Jersey Democrat Bill Pascrell because of congressional redistricting, he put out a video showing the blustery Mr. Pascrell appearing tongue-tied in an MSNBC interview. Pascrell spokesman Sean Darcy retorted: “This video is disingenuous to the point of being laughable.”

More recently, new Iowa Republican Sen. Joni Ernst of Iowa said that when Mr. Obama vowed to work closely with her party after the GOP’s huge gains in the midterm elections, his promise was, to her, “a little disingenuous. He’s had six years to work with Republicans, and now he’s offering a hand and being willing to sit down with Senator McConnell and our other soon-to-be colleagues.… He’s been so disengaged and not willing to work with Republicans or even some members of his own party.”

The Sunlight Foundation’s handy “Capitol Words” tool, which combs the Congressional Record, has found the usage of “disingenuous” has been fairly constant over the past two decades, with its usage between the parties split fairly evenly. The most frequent users? Now-retired Republican Sen. Judd Gregg of New Hampshire and McConnell’s arch-nemesis Harry Reid, the Senate minority leader.